DEV Community πŸ‘©β€πŸ’»πŸ‘¨β€πŸ’»

DEV Community πŸ‘©β€πŸ’»πŸ‘¨β€πŸ’» is a community of 966,904 amazing developers

We're a place where coders share, stay up-to-date and grow their careers.

Create account Log in
Cover image for NodeJS + Express part 5: Routes and Controllers
Eric The Coder
Eric The Coder

Posted on

NodeJS + Express part 5: Routes and Controllers

Here is a series of articles that will allow you to create backend applications with NodeJS + Express.

This series is the continuation of my series on the basics of NodeJS. If you don't have basic knowledge of NodeJS read this series first: Introduction to NodeJS

Node.js is today a must, so it is essential for a developer to master it.

So I will publish a new article about every two days and little by little you will learn everything there is to know about Node.js + Espress

To not miss anything follow me on twitter: https://twitter.com/EricTheCoder_


Express Router

As you seen in the previous article, creating a CRUD API with Express is easy. But you should have notice by now that all that code in the same file is bulky and we will soon lose ourself.

By convention, Express developper split code in different files and folders to optimized code organisation.

The first and most obvious thing to do is to split the route and the route implementation codes.

Here a exemple we use in the previous article

app.get('/api/products/:productID', (req, res) => {
    const id = Number(req.params.productID)
    const product = products.find(product => product.id === id)

        if (!product) {
        return res.status(404).send('Product not found')
    }
    res.json(product)
})
Enter fullscreen mode Exit fullscreen mode

The goal here will be to split the route and his implementation code. To do that we can use an Express Package call Router

Router help to create a list of all your apps routes and associate them to a controller file that contain the implementation code.

First step is to create a file to put all our app routes. For exemple : /routes/products.js can contain all routes related to the product resource

And next step we will create a controller file to put all our routes implementation code. For exemple: /controllers/products.js

Starting from my previous article here an exemple of a route and a controller file.

routes/products.js

const express = require('express')
const router = express.Router()

const  { 
    getProducts,
    getProduct,
    createProduct,
    updateProduct,
    deleteProduct 
} = require('../controllers/products.js')

router.get('/', getProducts)

router.get('/:productID', getProduct)

router.post('/', createProduct) 

router.put('/:productID', updateProduct) 

router.delete('/:productID', deleteProduct)

module.exports = router
Enter fullscreen mode Exit fullscreen mode

As you can see the implementation is very easy and straightforward.

First create an instance to the Router object

Then import all the controller functions.

Lastly, use the router object to create a route and controller association.

Here is an exemple of the controller functions
controllers/products.js

const products = require('../data.js')

const getProducts = ((req, res) => {
    res.json(products)
})

const getProduct = ((req, res) => {
    const id = Number(req.params.productID)
    const product = products.find(product => product.id === id)

        if (!product) {
        return res.status(404).send('Product not found')
    }
    res.json(product)
})

const createProduct = ((req, res) => {
    const newProduct = {
        id: products.length + 1,
        name: req.body.name,
        price: req.body.price
    }
    products.push(newProduct)
    res.status(201).json(newProduct)
})

const updateProduct = ((req, res) => {
    const id = Number(req.params.productID)
    const index = products.findIndex(product => product.id === id)
    const updatedProduct = {
        id: products[index].id,
        name: req.body.name,
        price: req.body.price
    }

    products[index] = updatedProduct
    res.status(200).json('Product updated')
})

const deleteProduct = ((req, res) => {
    const id = Number(req.params.productID)
    const index = products.findIndex(product => product.id === id)
    products.splice(index,1)
    res.status(200).json('Product deleted')
})

module.exports = {
    getProducts,
    getProduct,
    createProduct,
    updateProduct,
    deleteProduct
}
Enter fullscreen mode Exit fullscreen mode

Nothing really new here, it's the same implementation but code are now in a separate functions with a req and res parameter.

Once the routes and controllers files are created we need to tell Express to use those routes

From the main file add a app.use() with our routes reference

const express = require('express')
const app = express()
const products = require('./data.js')
const products_routes = require('./routes/products.js')

app.listen(5000, () => {
    console.log('server is listening on port 5000')
})

app.use(express.json())
app.use('/api/products', products_routes)
Enter fullscreen mode Exit fullscreen mode

Noted, the app.use() have routes prefix in '/api/products' that mean all url path in the routes file will include that prefix automatically.

Conclusion

That's all for today, follow me on twitter: https://twitter.com/EricTheCoder_ to be notified of the publication of the next article (within two days).

Top comments (4)

Collapse
 
olsard profile image
olsard

Thanks for good structure example.

Collapse
 
louisnelza profile image
Louis Nel

Very neat. I like how you split the route and controllers into separate functions. Definitely something I will do in my code going forward.

Collapse
 
vikramparihar profile image
vikram parihar

Nice. You wrote this code in very good structure.

Collapse
 
ashlee380518 profile image
ashlee380518

Thank you.

πŸ‘‹ Welcome the newest DEV members

Head over to our Welcome Thread and say hello!